Numerous systems are known for the production of blended streams. For example, U.S. Pat. No. 6,186,193 discloses a method and apparatus providing for the continuous stream blending of two or more liquid streams. Each liquid stream is synchronously dosed in a mass ratio to a common mixing point. The flow of each stream is controlled by a digital on-off control. Each dose stream flow is produced and measured by a four element apparatus consisting of a servo motor and controller, a precision positive displacement pump, a mass meter, and a stream flow shut-off device. The servomotor and controller establish and control a periodic and intermittent flow rate required to displace a defined mass dose in a precisely defined flow interval. The system is said to be useful for blending components to produce a variety of industrial and commercial products.
U.S. Pat. No. 6,253,779 discloses a system for blending two-blend components to form a blended product. The system includes a first supply line for supplying a first blend component at a first flow rate and a second supply line for supplying a second blend component at a second flow rate. The first supply line and the second supply line intersect to form a blended product line. The system also includes a blended product measuring device positioned in the blended product line for measuring the flow rate of the blended product and an auxiliary measuring device positioned in the first supply line for measuring the flow rate of the first blend component. The system is said to be useful for blending products streams such as two gasoline streams having different octane levels to produce a third stream having yet another octane level.
U.S. Pat. No. 4,979,091 discloses a system for the blending of various streams having various flow rates and various concentrations. It is disclosed that the system continuously manipulates the composition of one of the streams being blended in such a manner that a blended product is provided which has a specified composition. The system is said to be useful for controlling the purity of the propane product from a refinery and for the continuous control of a gas or liquid blending where it is desired to meet a product specification by blending streams of various flow rates and composition. The patent discloses a system in which the composition of a blended propane product is monitored and feedback control is provided to control a de-ethanizer tower to increase or decrease the ethane content in one of the streams blended to produce the propane product.
U.S. Pat. Nos. 5,629,863; 5,871,634; 6,235,955; 6,436,863; and 6,732,796 disclose exemplary other known blending systems for production of various blended products.